Groped around fastening (4)
I believe the answer is:
rope
'fastening' is the definition.
'groped around' is the wordplay.
'around' indicates a hidden word.
'ROPE' can be found hidden inside 'groped'.
(Other definitions for rope that I've seen before include "Tier" , "will it bring in easy money when old?" , "Lash" , "Master of Suspense directed it" , "Hitchcock film" .)