Starts to bolster old material, putting card into flat caps and coats (6,7)
I believe the answer is:
bomber jackets
'coats' is the definition.
(bomber jacket is a kind of coat)
'starts to bolster old material putting card into flat caps' is the wordplay.
'starts to' indicates taking the first letters.
'old material putting' becomes 'om' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'card' becomes 'jack' (type of playing card).
'into' indicates putting letters inside.
'flat caps' becomes 'berets' (I've seen this in another clue).
The initial letter of 'bolster' is 'b'.
'jack' put into 'berets' is 'berjackets'.
'b'+'om'+'berjackets'='BOMBER JACKETS'
'and' is the link.
Can you help me to learn more?