Secured by peg, trousers put on (8)
I believe the answer is:
televise
'put on' is the definition.
(I've seen this before)
'secured by peg trousers' is the wordplay.
'secured by' is an insertion indicator (inserted letters are held or secured).
'peg' becomes 'tee' (tee is a kind of peg).
'trousers' becomes 'levis' (Levi's is an example).
'tee' going around 'levis' is 'TELEVISE'.
(Other definitions for televise that I've seen before include "Show" , "Broadcast visual images" , "Air, broadcast" , "Screen" , "Put on TV (S, not Z)" .)