Long Weekend solution
by Kegler

Five answers start with MON, and another five start with FRI.  If you follow the    
instructions at 29 Across, i.e., TAKE THE DAY OFF, you get a “long weekend.”

Long Weekend solution grid

Across
1M(ISH)AP (HIS anag)
7S + TRESS
11ENOC + H (H + CONE rev)
12IN(K)S
13{M(ON)}ARCH
14L + ONE + R
15hAIRY
17GANJA (hidden)
18{F(RI)}ABLE
19WEE + P (EWE anag)
20{M(ON}E + YE)D
22LOOP + Y (LOOP rev)
26USER (RUSE anag)
28DESI (hidden)
29TAKE THE DAY OFF
31O + GEE
33V + END
36{FR(I}AR)IES (AIR anag)
38TYRO (TROY anag)
40ITCH (hidden)
42STAG (GATS rev)
43O + VOID
45EMIT (TIME rev)
46LOCHS ("LOCKS" hom)
47ELAN (LANE anag)
48FLEE ("FLEA" hom)
49{F + RI}SKIER
50RIDDLE (2 defs)
51TENONS (NONETS anag)
Down
1MERG + E (GERM anag)
2IN + LAYS
3{MO(N} + SO)ON
4A + H(E)AD
5P(I)RATE
6UNABBREVIATED (VENUE A BIT DRAB anag)
7S + KILLED
8RAY (even letters)
9ERSE (SEER anag)
10SH(OPL)IFT (POL anag)
16{MON}(K)EYS
21ESKER (REEKS anag)
23O + RAN
24PEONY (2 defs, pun)
25ATOMIZER (AMORTIZE anag)
27STYE ("STY" hom)
30HO(STI)LE (IT'S rev)
32{F(RI}G)ATE
34EAGLET (LEGATE anag)
35ARISEN (A SIREN anag)
37{MO(N}GOOS)E (GOONS anag)
39ODORS (hidden)
41C(L)AD
44O + HI + O
45{F(R)I}END