Looking at English houses you start to invest (6)
I believe the answer is:
eyeing
'looking at' is the definition.
(I've seen this in another clue)
'english houses you start to invest' is the wordplay.
'english' becomes 'eng' (abbreviation).
'houses' means one lot of letters goes inside another.
'you' becomes 'ye' (historical version of 'you').
'start to' says to take the initial letters.
The initial letter of 'invest' is 'i'.
'ye'+'i'='yei'
'eng' placed around 'yei' is 'EYEING'.
(Other definitions for eyeing that I've seen before include "Gazing" , "Looking intently at" , "Foliage" , "Looking at, watching" , "Watching closely" .)