Loosen tight nut, white perhaps? (7)
I believe the answer is:
untwine
'loosen' is the definition.
(untwine can mean to loosen or undo)
'tight nut white perhaps?' is the wordplay.
'tight' indicates anagramming the letters (tight can mean drunk).
'white perhaps?' becomes 'wine' (white is a type of wine).
'nut' with letters rearranged gives 'unt'.
'unt'+'wine'='UNTWINE'
(Other definitions for untwine that I've seen before include "Unwind; untwist" , "free?" , "Separate" , "Release" , "Ravel to be dealt with" .)