Prince Henry in river to breathe out (6)
I believe the answer is:
exhale
'breathe out' is the definition.
(synonyms)
'prince henry in river' is the wordplay.
I cannot really understand how this works, but
'prince' could be 'hal' (I've seen this before) and 'hal' is found in the answer.
'river' could be 'exe' (River Exe) and 'exe' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
'to' is the link.
Can you help me to learn more?
(Other definitions for exhale that I've seen before include "Expel air from the lungs" , "Breathe out" , "Joint of chicken" , "Give out" , "expire" .)