Answer: ADDSTO

AnswerCrossword Clue
ADDSTOExpands, as a deck
ADDSTOExpands
ADDSTOBuilds up
ADDSTOBroadens
ADDSTOPuts in something new
ADDSTOPiles on
ADDSTOExtends
ADDSTOPuts with
ADDSTOEnlarges.
ADDSTOComplicates
ADDSTOEnlarges
ADDSTOSupplements
ADDSTOBuilds on
ADDSTOPuts more in
ADDSTOAugments
ADDSTOIncreases
ADDSTOCombines with
ADDSTOBuilds a deck for, say
ADDSTOEnhances
ADDSTOComplements
ADDSTOMakes more comprehensive