Thwarted swimmer longed to enter northerly place to surf well (7,5)

'thwarted swimmer' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'longed to enter northerly place to surf well' is the wordplay.
'longed' becomes 'ached' ('ache' can be a synonym of 'long').
'to enter' means one lot of letters goes inside another.
'northerly' says the letters should be written backwards (in a down clue, letters go up or 'north').
'place to surf' becomes 'web' (as in surfing the web).
'well' becomes 'hale' (I've seen this before).
'web' reversed gives 'bew'.
'ached' placed into 'bew' is 'beachedw'.
'beachedw'+'hale'='BEACHED WHALE'

Can you help me to learn more?