Request with regard to investing £1000 (3,3)
I believe the answer is:
ask for
'request' is the definition.
(synonyms)
'with regard to investing ps1000' is the wordplay.
'with regard to' becomes 'as for' ('as for' means 'as regards' or 'with regard to').
'investing' indicates putting letters inside (inserted letters are taken in or invested).
'psk000' becomes 'k' (I can't explain this - if you can you should believe this answer much more).
'asfor' going around 'k' is 'ASK FOR'.
Can you help me to learn more?
(Other definitions for ask for that I've seen before include "Make a request" , "Demand" .)