Many exploit a short term dreamer (5-5)
I believe the answer is:
lotus-eater
'dreamer' is the definition.
(thesaurus)
'many exploit a short term' is the wordplay.
'many' becomes 'lot' (a lot of something).
'exploit' becomes 'use' (use can mean to exploit).
'short term' becomes 'ter' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'lot'+'use'+'a'+'ter'='LOTUS-EATER'
Can you help me to learn more?
(Other definitions for lotus-eater that I've seen before include "Indolent person" , "One given to indulgence in pleasure and luxury" , "One indulging in pleasure and luxury, as described in Homer's Odyssey" , "One living indolently - mythical person met by Odysseus in North Africa" .)