Alison and I are involved in affair (7)
I believe the answer is:
liaison
'affair' is the definition.
('liaison' can be a synonym of 'affair')
'alison and i are involved' is the wordplay.
'and' means one lot of letters go next to another (I've seen this in other clues).
'are involved' is an anagram indicator (involved can mean confusing or complex).
'alison' put after 'i' is 'ialison'.
'ialison' with letters rearranged gives 'LIAISON'.
'in' is the link.
(Other definitions for liaison that I've seen before include "sexual adventure" , "Mutual communication and co-operation" , "Intimate relationship" , "A contact or affair" , "Sort of officer" .)