Smallest musical note presented with hesitation (7)
I believe the answer is:
minimum
'smallest' is the definition.
('minimum' can be similar in meaning to 'smallest')
'musical note presented with hesitation' is the wordplay.
'musical note' becomes 'minim' (minim is a kind of musical note).
'presented with' means one lot of letters go next to another.
'hesitation' becomes 'um'.
'minim'+'um'='MINIMUM'
(Other definitions for minimum that I've seen before include "Least recorded value" , "The least of smallest amount possible" , "Nadir" , "Lower limit" , "Bottom" .)