Adherent gets new set secure (6)
I believe the answer is:
fasten
'secure' is the definition.
('fasten' can be a synonym of 'secure')
'adherent gets new set' is the wordplay.
'adherent' becomes 'fan'.
'gets' is an insertion indicator (gets can mean captures or absorbs).
'new' indicates an anagram.
'set' with letters rearranged gives 'ste'.
'fan' going around 'ste' is 'FASTEN'.
(Other definitions for fasten that I've seen before include "Shut" , "Tie or join together, fix firmly" , "Affix" , "Tie, secure" , "Bolt" .)