Finishing Touches
by Kegler

Exactly one-half (20) of the clues contain an extra letter, always in the definition.   In clue order, these letters spell a five-word phrase.

Finishing Touches grid

Across
1Had a particular attitude about it suggested (7)
6Place fill-in operator (5)
11Chopper circling gym's moist elevated location (4)
12Drunk has an inexpensive source of metals (7)
13Stay put in a new position, we hear (6)
14Local dialect unusual to Pisa (6)
15Per Rev. Spooner, kick back with a plop (4,4)
16Pull an American League player (4)
17Tapes remixed; hit heard (5)
20Lied to Mr. Rocky with experienced tone (3-5)
23Hint about ingredient in beer and unknown Chinese restaurant dish (4,4)
26Vast emptiness holds allure (5)
30Escaped agent has left (4)
32Discussed a door, a stock-buyer's chute (8)
33Ruin returning officeholder briefly chasing young woman (6)
34In a way, disguise entrance to cafeteria in eastern junction (6)
35Ring one of GPs enthralled by Ms. Shire's earache (7)
36Surprisingly slow nocturnal hunters (4)
37Scandinavians snore, unfortunately (5)
38Fools clutching Times and pints (7)
Down
1Normal limits for toy dog (5)
2Aspiring soprano and top-notch salesman love musical dramas (6)
3Slower part of a piano duet; having this, God is good? (7)
4Tantalize initially by lifting black coat's mink decorations (7)
5Bank announced poor grade in writing (6)
7Get one board from nine rat chewed up (7)
8Cries as iodine finally enters cuts (5)
9First of patients runs in time to make a copay (5)
10Roy sets out seafood appetizers (7)
12Quilting party hosts British actress Neuwirth (4)
18Raised drink at company's shapely figure? (7)
19Insult father brought up describing lady's face is horrifying (7)
21Tyrone directed New York's oppressive power (7)
22Agnes heard Gibson is short (7)
24Ushers at the entrance to Ms. Zadora's perfect palace (6)
25Must have a couple of lengths for sewing kilt component (6)
27Certain mouse's time to ... (5)
28...roam wildly, taking taste of leftover grinder (5)
29Navy leaves battlefield zone (4)
31Feature of lesser designer's rejected outfit for Marty? (5)

Solution