Walk open-armed when upset (9)
I believe the answer is:
promenade
'walk' is the definition.
(promenading is a kind of walking)
'open-armed when upset' is the wordplay.
'when upset' is an anagram indicator.
'open'+'armed'='openarmed'
'openarmed' is an anagram of 'PROMENADE'.
(Other definitions for promenade that I've seen before include "Esplanade" , "Place for strolling by the sea" , "dance" , "Seaside walkway" , "Seaside walk?" .)