Endless things for tiller to do in London area (4)
I believe the answer is:
soho
'london area' is the definition.
(I've seen this before)
'endless things for tiller' is the wordplay.
'endless' means to look at the middle letters.
'things' becomes 'flagships' (flagship is a kind of thing).
'for tiller' becomes 'oho' (I can't justify this - if you can you should give a lot more credence to this answer).
The central letter of 'flagships' is 's'.
's'+'oho'='SOHO'
'to do in' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
(Other definitions for soho that I've seen before include "Central London entertainment area" , "foreign quarter" , "London area renowned for nightlife" , "Nightclub area in London" , "Call a large market for software" .)