At one point, Doctor Who's in Time Lord trousers by Top Shop (5,7)

'at one point doctor who's' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'time lord trousers by top shop' is the wordplay.
'time' becomes 't' (abbreviation).
'lord' becomes 'peer' (peer is a kind of lord).
'trousers' indicates putting letters inside (trouser can mean to steal or take).
'by top shop' becomes 'capaldi' (I can't justify this - if you can you should give a lot more credence to this answer).
't' placed inside 'peer' is 'peter'.
'peter'+'capaldi'='PETER CAPALDI'

'in' is the link.

Can you help me to learn more?