Element drunk? That man's round the bend (7)
I believe the answer is:
lithium
'element' is the definition.
(lithium is a kind of element)
'drunk? that man's round the bend' is the wordplay.
I cannot quite see how this works, but
'drunk?' could be 'lit' (slang term) and 'lit' is present in the answer.
'bend' could be 'u' (a U-bend is a kind of bend - pipe under sink) and 'u' is present in the answer.
'man' could be 'hi' and 'hi' is found in the answer.
A single letter 'm' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for lithium that I've seen before include "Chemical element (Li), used in batteries" , "Lightest-known metal" , "Soft silvery element" , "Silver-white metal (symbol: Li)" , "Lightest metallic element" .)