You finally invested in more extended seat by the pool? (7)
I believe the answer is:
lounger
'seat by the pool?' is the definition.
I can't tell whether this definition defines the answer.
'you finally invested in more extended' is the wordplay.
'finally' says to take the final letters.
'invested in' means one lot of letters goes inside another.
'more extended' becomes 'longer' ('long' can be similar in meaning to 'extended').
The final letter of 'you' is 'u'.
'u' going into 'longer' is 'LOUNGER'.
Can you help me to learn more?
(Other definitions for lounger that I've seen before include "Comfortable seat" , "Casual coat" , "Reclining chair" , "Adjustable couch - loose leisure garment" , "Relax on this" .)