T S Eliot play shows understatement (7)
I believe the answer is:
litotes
'understatement' is the definition.
(I've seen this before)
't s eliot play' is the wordplay.
'play' indicates an anagram.
't'+'s'+'eliot'='tseliot'
'tseliot' with letters rearranged gives 'LITOTES'.
'shows' acts as a link.
(Other definitions for litotes that I've seen before include "in which not a little is a lot?" , "Rhetorical understatement - toilets (anag)" , "No small task, for example" , "Ironical understatement (grammar)" , "No exaggeration" .)