Twisted ungodly act -- occasionally it could be gripping (5)
I believe the answer is:
'it could be gripping' is the definition.
(a talon may grip things)
'twisted ungodly act occasionally' is the wordplay.
'twisted' says the letters should be written backwards.
'occasionally' indicates alternate letters.
The alternating letters of 'ungodlyact' are 'nolat'.
'nolat' in reverse letter order is 'TALON'.
(Other definitions for talon that I've seen before include "Large claw" , "Eagle claw" , "One may be grabbing" , "ogee moulding" , "Hooker" .)