Boxer you observed during air journey cuddling wife (9)
I believe the answer is:
flyweight
'boxer' is the definition.
(flyweight is a kind of boxer)
'you observed during air journey cuddling wife' is the wordplay.
'you' becomes 'ye'.
'observed during' indicates putting letters inside.
'air journey' becomes 'flight' (I've seen this before).
'cuddling' is an insertion indicator.
'wife' becomes 'w'.
'ye' placed into 'flight' is 'flyeight'.
'flyeight' placed around 'w' is 'FLYWEIGHT'.
(Other definitions for flyweight that I've seen before include "Small, aggressive man" , "fighter" , "Boxer in the lightest category" , "Boxing category" , "Sort of boxer" .)