Praise from firm met with a grunt -- working after hours? (12)
I believe the answer is:
congratulate
'praise' is the definition.
(congratulating is a kind of praising)
'firm met with a grunt working after hours?' is the wordplay.
'firm' becomes 'co' (a firm is a company).
'met' says to put letters next to each other.
'with' is an insertion indicator.
'working' indicates anagramming the letters.
'after hours?' becomes 'late' (during late hours).
'grunt' anagrammed gives 'ngrtu'.
'a' put inside 'ngrtu' is 'ngratu'.
'co'+'ngratu'+'late'='CONGRATULATE'
'from' is the link.
(Other definitions for congratulate that I've seen before include "Wish joy to" , "Praise (someone) for an achievement" , "Compliment" .)