You can't trust us, stealing pounds and getting the boot! (6)
I believe the answer is:
wellie
'the boot' is the definition.
(I've seen this before)
'you can't trust us stealing pounds' is the wordplay.
'you can't trust us' becomes 'we lie'.
'stealing' indicates putting letters inside.
'pounds' becomes 'L' (abbreviation e.g. Lsd - pounds, shillings, pence).
'welie' going around 'l' is 'WELLIE'.
'and getting' is the link.
(Other definitions for wellie that I've seen before include "Rubber boot" , "Greek letter" , "Waterproof boot" , "footwear" , "energy" .)