Crossword Genius

It's hard to carry, making you grumpy (5)

Ross

I believe the answer is:

cross

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'grumpy' is the definition.
(synonyms)

I can't explain the remainder of the clue.

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(Other definitions for cross that I've seen before include "Annoyed; symbol" , "Traverse - displeased" , "means of execution" , "Grouchy" , "frustrated?" .)

I've seen this clue in The Times.
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