John Betjeman's third poet recalled (6)
I believe the answer is:
toilet
'john' is the definition.
(synonyms)
'betjeman's third poet recalled' is the wordplay.
'betjeman's third' becomes 't' (3rd letter of 'betjeman').
'poet' becomes 'eliot' (TS Eliot).
'recalled' is a reversal indicator.
't'+'eliot'='teliot'
'teliot' written backwards gives 'TOILET'.
(Other definitions for toilet that I've seen before include "Plumbing fixture" , "It means washing" , "Lavatory paper" , "something to go on?" , "Waste disposal unit" .)