Jump on insects, getting tons inside shorts (3,5)
I believe the answer is:
hot pants
'shorts' is the definition.
(I've seen this before)
'jump on insects getting tons' is the wordplay.
'jump' becomes 'hop' (hop is a kind of jump).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'insects' becomes 'ants' (ant is a kind of insect).
'getting' is an insertion indicator.
'tons' becomes 't'.
'hop'+'ants'='hopants'
'hopants' going around 't' is 'HOT PANTS'.
'inside' acts as a link.
(Other definitions for hot pants that I've seen before include "revealing attire" , "Women's very brief shorts" , "Brief skin-tight shorts worn by young women" , "These highlight bottom" , "Skimpy garment" .)