One gushes in speech for bloke (6)
I believe the answer is:
geezer
'for bloke' is the definition.
(synonyms)
'one gushes in speech' is the wordplay.
'one gushes' becomes 'geyser' (geysers gush water).
'in speech' shows a homophone (sound like).
'geyser' sounds like 'GEEZER'.
(Other definitions for geezer that I've seen before include "Old eccentric chap" , "A man (colloq.)" , "Old man (sl)" , "Eccentric man, usually old" , "Fellow (slang)" .)