I'm much tickled by swimmer having relaxed posture (7)
I believe the answer is:
lolling
'relaxed posture' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives can sometimes define each other.
'i'm much tickled by swimmer' is the wordplay.
I cannot really see how this works, but
'swimmer' could be 'ling' (ling is a kind of aquatic vertebrate) and 'ling' is found within the answer.
The remaining letters 'lol' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'having' is the link.
Can you help me to learn more?
(Other definitions for lolling that I've seen before include "Lounging, slouching" , "Lounging around" , "Sprawling" , "Lying lazily about" , "Loafing, lounging" .)