Like fatty substance primarily located deep in Scottish river (7)

I believe the answer is:

tallowy

I'm a little stuck... Click here to teach me more about this clue!

'located deep in scottish river' is the definition.
The answer and definition are not the same part of speech. However, adjectives and past participle verbs can occasionally define each other.

'like fatty substance primarily' is the wordplay.
'like' becomes 'y' (similar in meaning).
'fatty substance' becomes 'tallow' (I've seen this in another clue).
'primarily' is a charade indicator (letters next to each other).
'y' after 'tallow' is 'TALLOWY'.

Can you help me to learn more?

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app