Playing rough, she made a mess of my boot (6)
I believe the answer is:
tomboy
'playing rough she made a mess' is the definition.
I can't judge whether this definition defines the answer.
'of my boot' is the wordplay.
'of' is an anagram indicator (the answer comes from or 'of' the letters).
'my'+'boot'='myboot'
'myboot' with letters rearranged gives 'TOMBOY'.
Can you help me to learn more?
(Other definitions for tomboy that I've seen before include "Girl who enjoys being laddish" , "Girl enjoying rough outdoor activities" , "Girl dressed in a masculine manner" , "Girl said to be exhibiting boyish behaviour" , "Girl who likes rough and noisy activities" .)