Like a Christmas tree cross (7)
I believe the answer is:
needled
'like' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives sometimes define each other.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for needled that I've seen before include "Provoked or teased with knitting implements? (7)" , "bugged" , "Goaded or provoked" , "Piqued" , "Irked" .)