Sailing east, perhaps, with a heavy heart (2,3)
I believe the answer is:
at sea
'sailing' is the definition.
(synonyms)
'east perhaps with a heavy heart' is the wordplay.
'perhaps with' indicates anagramming the letters.
'heart' says to take the centre.
The centre of 'heavy' is 'a'.
'east' mixed up with 'a' makes 'AT SEA'.
(Other definitions for at sea that I've seen before include "Thrown" , "Not knowing whether you're coming or going" , "On a moving ship?" , "cruising?" , "Totally disorganised" .)