Sailing east, perhaps, with heavy heart (2,3)
I believe the answer is:
at sea
'sailing' is the definition.
(synonyms)
'east perhaps with heavy heart' is the wordplay.
'perhaps with' is an anagram indicator.
'heart' indicates the central letters.
The central letter of 'heavy' is 'a'.
'east' mixed up with 'a' gives 'AT SEA'.
(Other definitions for at sea that I've seen before include "cruising?" , "Mixed up" , "Away from land" , "sent in junk?" , "Lost or confused - on the briny?" .)