Film dog in colour, one interrupting service (3,3,3)
I believe the answer is:
rin tin tin
'film dog' is the definition.
(famous Hollywood dog)
'in colour one interrupting service' is the wordplay.
'colour' becomes 'tint' (tint is a kind of colour**).
'one' becomes 'i' (Roman numeral).
'interrupting' indicates putting letters inside.
'service' becomes 'rn' (abbreviation for Royal Navy).
'in'+'tint'+'i'='intinti'
'intinti' inserted inside 'rn' is 'RIN TIN TIN'.
(Other definitions for rin tin tin that I've seen before include "shot dog" , "Canine star of many films" , "Fabled canine" , "Dog Star" .)