Passing one chap pinning hairstyle with fancy net (11)
I believe the answer is:
impermanent
'passing one chap pinning' is the definition.
'impermanent' can be an answer for 'passing' (thesaurus). I'm unsure of the 'one chap pinning' bit.
'hairstyle with fancy net' is the wordplay.
'hairstyle' becomes 'permanent' (permanent is a kind of hairstyle).
'with' means one lot of letters go next to another.
'fancy net' becomes 'im' (I can't explain this - if you can you should give a lot more credence to this answer).
'permanent' put after 'im' is 'IMPERMANENT'.
(Other definitions for impermanent that I've seen before include "Temporary" , "Not lasting" , "Mutable" , "Transient" , "Transitory" .)