Ruling line in colour almost ugly (7)
I believe the answer is:
dynasty
'ruling line' is the definition.
'dynasty' can be an answer for 'line' (dynasty is a kind of line). I am not certain of the 'ruling' bit.
'colour almost ugly' is the wordplay.
'colour almost' becomes 'dy' (I can't explain this - if you can you should give a lot more credence to this answer).
'ugly' becomes 'nasty' (I've seen this in another clue).
'dy'+'nasty'='DYNASTY'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for dynasty that I've seen before include "Line of kings" , "Succession of relatives" , "royal family" , "Family of successive rulers" , "show" .)