Mostly head around salt lake (7)
I believe the answer is:
ontario
'lake' is the definition.
(I know that Ontario is a lake)
'mostly head around salt' is the wordplay.
I cannot quite understand how this works, but
'around' could be 'o' (a round letter) and 'o' is found within the answer.
'salt' could be 'tar' (both can informally mean a sailor) and 'tar' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ontario that I've seen before include "city" , "Most easterly Great Lake" , "one of the provinces" , "Oration in Canadian province" , "One of the Great Lakes" .)