In fact swimmer gets unravelled (7)

I believe the answer is:

decoded

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

'unravelled' is the definition.
Although both the answer and definition are past participle verbs, I can't understand how one could define the other.

'in fact swimmer' is the wordplay.
'in' means one lot of letters goes inside another.
'fact' becomes 'deed'.
'swimmer' becomes 'cod' (cod is a kind of aquatic vertebrate).
'deed' going around 'cod' is 'DECODED'.

'gets' is the link.

Can you help me to learn more?

I've seen this clue in The Hindu.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.