A wet fellow apt to fall down (4)
I believe the answer is:
drip
'a wet' is the definition.
(thesaurus)
'fellow apt to fall down' is the wordplay.
I cannot quite see how this works, but
'down' could be 'd' and 'd' is present in the answer.
The remaining letters 'rip' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for drip that I've seen before include "Fall from a leaking tap - weakling" , "Flow in small drops" , "Insubstantial person - trickle" , "Small drop; ineffectual person" , "Weak and ineffectual person" .)