Understand harvest is put together (6)
I believe the answer is:
gather
I believe this clue is a triple definition!
'understand' is the first definition.
(synonyms)
'harvest' is the second definition.
(I've seen this before)
'is put together' is the third definition.
(thesaurus)
(Other definitions for gather that I've seen before include "Collect; understand" , "The rag (anag.)" , "Accumulate, garner" , "Collect together in one place" , "Assemble; understand" .)