Lose mass on Scottish isle (6)

I believe the answer is:
mislay
'lose' is the definition.
(synonyms)
'mass on scottish isle' is the wordplay.
I cannot quite see how this works, but
'mass' could be 'm' (symbol used in Physics e.g. f=ma) and 'm' is found within the answer.
'isle' could be 'islay' (Scottish island) and 'islay' is found within the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for mislay that I've seen before include "Lose track of" , "Lose (an item)" , "Be unable to find" , "Lose (something)" , "Put in wrong place, lose temporarily" .)