Lint is involved in fix (6)
I believe the answer is:
instil
'fix' is the definition.
(I've seen this before)
'lint is involved' is the wordplay.
'involved' indicates an anagram (involved can mean confusing or complex).
'lint'+'is'='lintis'
'lintis' is an anagram of 'INSTIL'.
'in' acts as a link.
(Other definitions for instil that I've seen before include "Drill" , "Inject as in list" , "It's nil (anag.)" , "Introduce into mind, being in list" , "Implant (in the mind)" .)