Compact steer gone mad (5)
I believe the answer is:
terse
'compact' is the definition.
(terse can mean compact or brief in speech)
'steer gone mad' is the wordplay.
'gone mad' indicates anagramming the letters.
'steer' with letters rearranged gives 'TERSE'.
(Other definitions for terse that I've seen before include "Short and sharp" , "Crisp and brief" , "Succinct about trees" , "Sententious" , "precise" .)