Fashionable rock fan’s last to leave metal bar (5)

I believe the answer is:
ingot
'metal bar' is the definition.
(synonyms)
'fashionable rock fan's last to leave' is the wordplay.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'rock fan's last' becomes 'tog' (I can't explain this - if you can you should give a lot more credence to this answer).
'to leave' says the letters should be written in reverse (I've seen 'left' mean this).
'tog' back-to-front is 'got'.
'in'+'got'='INGOT'
Can you help me to learn more?
(Other definitions for ingot that I've seen before include "Pig" , "Bar of bullion, for example" , "this must be cast" , "Piece of cast metal" , "Mass of precious metal" .)
