He perhaps requires odd bits of glass (3)
I believe the answer is:
gas
'he perhaps' is the definition.
(he is a kind of gas)
'odd bits of glass' is the wordplay.
'odd bits of' indicates alternate letters.
The alternate letters of 'glass' are 'GAS'.
'requires' acts as a link.
(Other definitions for gas that I've seen before include "Talk excessively" , "See 2" , "rabbit" , "Hydrogen or oxygen, say" , "Form of fossil fuel" .)