The most common and most likely answer to this crossword clue is the 4 letter word VIED
V
I
E
D
Buddy explains!

The straight part
We know that "struggled" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case struggled = vied.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does VIED mean?
VIED verb- To fight for superiority; to contend; to compete eagerly so as to gain something.
- To rival (something), etc.
- To do or produce in emulation, competition, or rivalry; to put in competition; to bandy.
- To stake; to wager.
- To stake a sum of money upon a hand of cards, as in the old game of gleek. See revie.