See the pound slipped inside as an insult (6)
I believe the answer is:
slight
'insult' is the definition.
(I've seen this before)
'see the pound slipped inside' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'pound' could be 'l' (abbreviation e.g. Lsd - pounds, shillings, pence) and 'l' is found in the answer.
The remaining letters 'sigh' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'as an' acts as a link.
Can you help me to learn more?
(Other definitions for slight that I've seen before include "Deliberate discourteous act" , "Small, snub" , "Slim or tenuous" , "slap in the face" , "Snub - not much!" .)