Left at sea, aim to make forecast (7)
I believe the answer is:
portend
'forecast' is the definition.
(synonyms)
'left at sea aim' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'at' says to put letters next to each other.
'sea aim' becomes 'end' (I've seen this before. I am not sure about the 'sea' bit.).
'port'+'end'='PORTEND'
'to make' is the link.
Can you help me to learn more?
(Other definitions for portend that I've seen before include "Presage, bode" , "Threaten" , "forecast" , "Give warning" , "Be a sign of something to come" .)