Heard bloke in hot spring (6)
I believe the answer is:
geyser
'hot spring' is the definition.
(I've seen this before)
'heard bloke' is the wordplay.
'heard' shows a homophone (sound like).
'bloke' becomes 'geezer' (synonyms).
'geezer' is a homophone of 'GEYSER'.
'in' acts as a link.
(Other definitions for geyser that I've seen before include "Spring that discharges steam and hot water" , "Spring discharging hot water and steam" , "Fountain of hot water from natural spring" , "upsurge" , "It blows off steam" .)