At the start of an affair, she makes a bundle (5)
I believe the answer is:
sheaf
'a bundle' is the definition.
(synonyms)
'at the start of an affair she makes' is the wordplay.
'at' says to put letters next to each other.
'the start of' suggests taking the first letters.
'makes' becomes 'f' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The first letter of 'affair' is 'a'.
'a' after 'she' is 'shea'.
'shea'+'f'='SHEAF'
Can you help me to learn more?
(Other definitions for sheaf that I've seen before include "Bundle, as of reeds for thatching" , "Bundle of wheat" , "Bundle of cereal plants" , "Stack, bundle" , "Reaper's bundle" .)