Dan set terribly neat tempo (7)
I believe the answer is:
andante
'tempo' is the definition.
(andante is a kind of tempo)
'dan set terribly neat' is the wordplay.
'set' is an anagram indicator (instruction to set the letters).
'terribly' is an anagram indicator.
'dan' is an anagram of 'and'.
'neat' anagrammed gives 'ante'.
'and'+'ante'='ANDANTE'
(Other definitions for andante that I've seen before include "Moving fairly slowly" , "progressing slowly" , "moving unhurriedly" , "not hurrying from bar to bar" , "Noted instruction" .)