A lot of old bread brought up for Picasso, say (5)
I believe the answer is:
pablo
'picasso say' is the definition.
The definition suggests a singular noun which matches the answer.
'a lot of old bread brought up' is the wordplay.
'a lot of' means to remove the last letter (a lot of but not all of the word).
'bread' becomes 'bap' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'brought up' shows that the letters should be reversed in order (in a down clue, letters go up).
'old' with its final letter taken away is 'ol'.
'ol'+'bap'='olbap'
'olbap' backwards is 'PABLO'.
'for' is the link.
Can you help me to learn more?
(Other definitions for pablo that I've seen before include "man of La Mancha?" , "Foreign fellow" , "and 13 Down: Spanish artist" , "Picasso's name" , "-- Picasso, Spanish artist" .)