Suffer when popular remedy is depleted (5)
I believe the answer is:
incur
'suffer' is the definition.
(to incur is to suffer or experience)
'popular remedy is depleted' is the wordplay.
I cannot really understand how this works, but
'popular' could be 'in' (something that's 'in' is fashionable) and 'in' is present in the answer.
The remaining letters 'cur' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'when' acts as a link.
Can you help me to learn more?
(Other definitions for incur that I've seen before include "Bring something on oneself, often unpleasant" , "Become subject to (eg, taxes)" , "Bring on as a consequence" , "Become subject to (something unwelcome)" , "Run up" .)