Endless passion and desire after gulping down drug (5,4)
I believe the answer is:
angel dust
'drug' is the definition.
(angel dust is a kind of drug)
'endless passion and desire after gulping down' is the wordplay.
I cannot quite understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is found within the answer.
'down' could be 'd' and 'd' is found in the answer.
'passion' could be 'lust' (I've seen this before) and 'lust' is present in the leftover letters.
The remaining letters 'age' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for angel dust that I've seen before include "Hallucinogen - stale dung (anag)" , "Drug" .)