Fix group of ships heading in opposite direction (4)
I believe the answer is:
nail
'fix group of ships' is the definition.
'nail' can be an answer for 'fix' (I've seen this before). I'm unsure of the 'group of ships' bit.
'heading in opposite direction' is the wordplay.
'heading' is a charade indicator (letters next to each other) (some letters go in front of or head others).
'in opposite' becomes 'ail' (I can't explain this - if you can you should give a lot more credence to this answer).
'direction' becomes 'N' (compass direction north).
'ail' put after 'n' is 'NAIL'.
Can you help me to learn more?
(Other definitions for nail that I've seen before include "Metal fastener" , "stud" , "Hammer's target" , "Growth on digit" , "Spike, fasten" .)