Sharing problems aboard? (2,3,4,4)
I believe the answer is:
in the same boat
'sharing problems' is the definition.
(people sharing a problem are in the same boat)
'aboard?' is the wordplay.
I cannot quite understand how this works, but
'aboard?' could be 'in' (I've seen this in other clues) and 'in' is present in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for in the same boat that I've seen before include "Suffering similar circumstances" , "like shipmates" , "like the Owl and the Pussy-Cat" , "Suffering identical circumstances" , "Sharing unfortunate circumstances" .)