Flag excursion around Rhode Island with colonel (9)
I believe the answer is:
tricolour
'flag' is the definition.
(tricolour is a kind of flag)
'excursion around rhode island with colonel' is the wordplay.
'excursion' becomes 'tour' (I've seen this before**).
'around' means one lot of letters goes inside another.
'rhode island' becomes 'ri' (US postal abbreviation).
'with' means one lot of letters go next to another.
'colonel' becomes 'col'.
'ri'+'col'='ricol'
'tour' placed around 'ricol' is 'TRICOLOUR'.
(Other definitions for tricolour that I've seen before include "Standard of French perhaps" , "French national flag" , "Having or involving three colours" .)