Send out Henry to cut a flower (6)
I believe the answer is:
exhale
'send out' is the definition.
(thesaurus)
'henry to cut a flower' is the wordplay.
'henry' becomes 'hal'.
'to cut' is an insertion indicator.
'a flower' becomes 'exe' (Exe is an English river).
'hal' placed within 'exe' is 'EXHALE'.
(Other definitions for exhale that I've seen before include "Give out" , "let breath out" , "Emit breath" , "Expel air from the lungs" , "expire" .)