Damp smell I had (5)
I believe the answer is:
humid
'damp' is the definition.
(I've seen this before)
'smell i had' is the wordplay.
'smell' becomes 'hum' (something with a bad smell is 'humming').
'i had' becomes 'I'd' (common contraction).
'hum'+'id'='HUMID'
(Other definitions for humid that I've seen before include "Muggy" , "Moist, warm (weather)" , "(Of atmosphere) with high water vapour content" , "Clammy" , "Close" .)