Poor Tom is a bit wet (5)
I believe the answer is:
moist
'a bit wet' is the definition.
(I've seen this before)
'poor tom is' is the wordplay.
'poor' is an anagram indicator.
'tom'+'is'='tomis'
'tomis' anagrammed gives 'MOIST'.
(Other definitions for moist that I've seen before include "Dampish" , "Damp, humid" , "Affected by tears, perhaps" , "Slightly wet, damp" , "sloppy" .)