Try to get off with trophy, seizing lid (4,2)
I believe the answer is:
chat up
'try to get off with' is the definition.
(to chat someone up is to attempt to seduce them)
'trophy seizing lid' is the wordplay.
'trophy' becomes 'cup' (cup is a kind of trophy).
'seizing' indicates putting letters inside.
'lid' becomes 'hat' (synonyms).
'cup' enclosing 'hat' is 'CHAT UP'.
(Other definitions for chat up that I've seen before include "Woo verbally" , "Flirt with (someone)" , "Engage (someone) in flirtatious talk" , "Talk flirtatiously to someone" , "Talk in romantic terms" .)