Father's about to turn out OK (7)
I believe the answer is:
approve
'ok' is the definition.
(to OK something is to approve it)
'father's about to turn out' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'about' says the letters should be written in reverse.
'to turn out' becomes 'prove' ('prove' can be a synonym of 'turn out').
'pa' reversed gives 'ap'.
'ap'+'prove'='APPROVE'
(Other definitions for approve that I've seen before include "Pronounce (something) satisfactory" , "Give sanctions to" , "Think highly of - sanction" , "Sanction, ratify" , "Pass" .)