The most common and most likely answer to this crossword clue is the 5 letter word TITAN
I've seen this crossword clue in The Times
T
I
T
A
N
More clues leading to the result TITAN
- One huge firm up for discussion
- Can rounds start to tire a heavyweight?
- Someone of great size I caught leaving doomed ship
- Colossus: it appears in bronze
- Giant bird sank, lacking wings
- Giant bird heads for Alpine nest
- Giant bird, and tailless
- Giant brown boxes appeal
- Magnetic attraction revealed in bronze colossus
- Giant bird with origins in Arabian Nights
Buddy explains!

The straight part
We know that "Giant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case giant = titan.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 TITAN mean?
TITAN noun- Something or someone of very large stature, greatness, or godliness.