Play sadly no Electra (9)
I believe the answer is:
tolerance
'play' is the definition.
(both can mean room for movement in engineering)
'sadly no electra' is the wordplay.
'sadly' indicates anagramming the letters.
'no'+'electra'='noelectra'
'noelectra' is an anagram of 'TOLERANCE'.
(Other definitions for tolerance that I've seen before include "Allowable variation (in a dimension)" , "Willingness to accept the beliefs of others" , "broad-mindedness" , "ecumenical spirit?" , "Allowance for dimensional inaccuracy" .)